I want to implement grid hierarchy (parent row has many child rows). Please refer to the link for reference - http://demos.telerik.com/kendo-ui/grid/hierarchy. How can it be implemented using Angularjs, ngGrid in asp.net web api project.
If you use ui-grid (the 3.0 version of ngGrid), then this is the expandable feature: http://ui-grid.info/docs/#/tutorial/306_expandable_grid
Expandable still has some gremlins in it, so you'll get some compromises and work arounds (or alternatively maybe need to submit some fixes), but it is the same concept.
You could use Angular Grid. The interface is similar to ng-grid. There is a 'test drive' section to see it demonstrated, where you can group by a column, giving a parent / child rows layout.